Centrifugal speed governors which produce a linear movement of an output member in response to movement of a sphere acting under centrifugal force are not new, as is evidenced by U.S. Pat. No. 2,775,665 to William H. Harstick. The Harstick governor includes a rotatable hollow casing having diverging inner tapering walls and a plurality of spheres placed in rolling contact with the diverging inner tapering walls. As is best shown by FIG. 1, the diverging inner tapering walls 35 cooperate with spherical members 37 and 38, and converging inner tapering walls 25 of plunger 27 such that movement of the spherical members 37 and 38 under centrifugal force will cause plunger 25 to be moved axially away from cylindrical casing 11. The Harstick invention does not provide, as does the invention described hereinafter, a rotatable hollow casing having multi-gradient inner tapered surfaces which cause an output member to undergo a slow linear movement in response to rotational speed less than or equal to a certain speed and undergo a rapid linear movement in response to rotational speeds which exceed a certain speed.
A typical centrifugal speed governor of the prior art is set forth in simplified form in U.S. Pat. No. 2,598,481 to Young. As is best seen in FIG. 3, the Young governor includes a cup-shaped holder 35 which is fixed for rotation upon a driven shaft 45. Holder 35 has formed within its interior a dished track 37 in which a number of flyballs 36 freely ride. As is apparent from FIG. 3, rotation of the holder 35 will cause flyballs 36 to move outward along dished track 37 until the flyballs 37 begin to push against and move longitudinally slidable member 38, such that displacement of the slidable member 38 will proceed gradually as rotational speed increases, until such time as either member 38 or flyballs 36 can be displaced no further (see FIG. 4). The Young invention does not provide a sudden, sharply defined displacement of an output member in response to a specified rotational speed, as does the invention described hereinafter.
Also included within the background art over which the subject invention is an improvement is the U.S. Pat. to D. M. MacMillin, No. 2,865,475. As is seen in FIGS. 1 and 2, the MacMillin invention includes a rotatable and axially movable cage 36 which is provided with arcuate radially extending slots 35 in each of which a ball 34 loosely resides. At a radially outward region of each slot 35 is disposed a control edge 38, ledge 39, and calibrating edge 40, whose arrangement is seen in FIG. 1 and enlarged in FIGS. 4 and 5. A ball control plate 30 having flat ball receiving surfaces 33 is mounted coaxially with cage 36 for rotation therewith, plate 30 being also axially fixed. The MacMillin invention provides for relative axial displacement between cage 36 and plate 30 when, as cage 36 and plate 30 begin to rotate, balls 34 move radially outward to control edge 38, at which point balls 34 contact surfaces 33 and thereby proceed to push cage 36 axially away from plate 30. The MacMillin invention does not provide, as does the subject invention, for an initial slow speed linear displacement of an output member in response to a sensed rotational speed less than or equal to a selected rotational speed and a final high speed linear displacement of an output member in response to a sensed rotational speed greater than a selected rotational speed.
Finally, the U.S. Pat. to Jouret, No. 4,107,483, shows the application of a typically configured speed governor within a movement of a timing apparatus. As shown in FIGS. 2 and 3, centrifugal mechanism, designated generally item 101, is seen to bring a pinion and pin switch 102 into intermittent engagement with timing wheel 12 and electrical contact assembly 103. Neither the Jouret invention or any of the aforementioned patents provides, as does the hereinafter described invention, for an economy of parts such that a centrifugal speed governor which actuates a power cutoff or torque disconnect is integrally located within a hub of a rotating work member, such as a planet gear which has a completely independent function.